1. Field of the Invention
The present invention relates to a camera such as a digital single-lens reflex camera.
2. Description of the Related Art
A single-lens reflex camera includes a main mirror and a sub-mirror both held (in a mirror-down position) between an imaging lens and an image pickup unit. At the startup of exposure, the main mirror and the sub-mirror are retracted (into a mirror-up position) from the mirror-down position between the imaging lens and the image pickup unit. After the end of the exposure, the main mirror and the sub-mirror are returned to the mirror-down position again.
In such a single-lens reflex camera, it is known to drive the sub-mirror between the mirror-down position and the mirror-up position by employing a toggle spring (see Japanese Patent Laid-Open No. 2011-85762). When the sub-mirror is driven between the mirror-down position and the mirror-up position by employing the toggle spring, the toggle spring is arranged such that the sub-mirror can be urged in a mirror-down direction at the mirror-down position and can be urged in a mirror-up direction at the mirror-up position.
However, when the sub-mirror is driven between the mirror-down position and the mirror-up position by employing the toggle spring, large torque is required to reverse an urging direction of the toggle spring. Accordingly, the above-mentioned mechanism is disadvantageous when the mirror has to be driven at a high speed.